Color stabilization of bright stock



2,832,741 COLOR STABILIZATION F BRIGHT STOCK Ralph I. Gottshali, Wiilow Grove, Pa, and John G.

Peters, Audubon,.N. 3., assignors to Gulf Oil (Zorporation, Pittsburgh, Pin, a corporation of Pennsylvania No Drawing. Application August 26, 1954 Serial No. 452,452 4 Claims. (Cl. 252-50) This invention relates to the color stabilization of bright stock type lubricating oils.

Bright stock is a high molecular weight lubricant produced by refining of cylinder stocks which are residual oils of high viscosity. It is desirable that bright stocks do not darken appreciably during storage and that they have high resistance to development of color during use. Because of their high viscosity and molecular weight, it is a problem to obtain color stabilizing materials which are readily soluble and remain soluble and active'therein. It has been proposed to stabilize lubricating oils with amines, see for instance U. S. Patent No. 1,888,023. We have found that certain primary aliphatic amines are unusually satisfactory for color stabilization of bright stocks whereas other amines are much less satisfactory or are unsatisfactory.

This invention has as an object the preparation of a bright stock containing an improved color stabilizing agent. Another object is to provide a bright stock containing a readily soluble color stabilizing agent. Another object is to provide a bright stock which has high color stability due to the presence of an improved color stabilizer. Other objects will appear hereinafter.

These and other objects are accomplished by our invention which includes a bright stock containing a primary amine having the formula R-NH in which R represents an alkyl group containing 12 to 24 carbon atoms at least one of which carbon atoms is in a side chain.

in the following description we have set forth several of the preferred embodiments of our invention, but it is to be understood that they are given by way of illustration and not in limitation thereof.

Bright stocks are well known in the prior art. They are obtained by refining high viscosity residual fractions of petroleum. These heavy residual fractions are known as cylinder stocks. They are usually of a dark color and are refined by various methods to produce a clear, high viscosity product known as a bright stock. Bright stocks usually vary in viscosity from about 125 S. U. S. at 210 F. to 300 S. U. S. at the same temperature. Our invention is applicable to all such bright stocks.

While all primary aliphatic amines having a branched chain structure of the type indicated above are satisfactory for color stabilization of bright stocks, we prefer to use aliphatic amines having a highly branched structure in the alkyl group. Secondary and tertiary alkyl groups are preferred. Particularly satisfactory amines are tertiary doecyl amine and its homologues containing up to 24 carbon atoms. This tertiary dodecyl amine and its homologues have the following formula:

wherein R equals one of the following: H-; CH CH3CH2;' 3 2 3) 3 Mixtures of tertiary alkyl primary amines of the above assarti Patented Apr. 29, 1%58 type and containing carbon atoms between C and C and between C and C are available commercially and constitute a preferred embodiment of our invention as stabilizers for bright stocks.

The stabilizers are added to the bright stock in an amount between .01 and 1.0 percent by weight depending upon the severity of the conditions to which the bright stock will be subjected. Ordinarily we prefer to add the ammine in an amount between about .01 and 0.1 percent by weight. These amines are readily soluble in the bright stock and may be dissolved therein with little or no heating. In most cases the amine may be incorporated by direct addition, preferably with stirring. It may be advantageous to first dissolve the amine in a small volume of the bright stock (with heating if necessary) and then incorporate the solution in the larger volume of bright stock.

The following experiments illustrate the improvement in stability obtained by using a branched chain amine in accordance with our invention. In these experiments the test samples were introduced into a 4-ounce glass bottle and a 0.5 inch by 3.0 inch polished copper strip was introduced into the glass bottle. The bottle was then placed in an oven maintained at a temperature of F. and was observed periodically for color darkening.

Four samples of a solvent refined S. U. S. (at 210 F.) Mid-Continent bright stock 10 pour were prepared. One sample was used as a control in the tests and no stabilizer was incorporated therein. The results obtained with this sample are shown in column 1 of Table I. In each of the other three samples 0.1 percent of amine additive was incorporated. In one sample the amine additive was a primary amine having a mean molecular weight of 267, a melting point of about 131 F. and constituted about 93 percent normal octadecyl primary amine with small amounts of normal hexadecyl primary amine and normal octadecenyl primary amine (Arrneen 18 manufactured by Armour and Company). The results obtained in the test with this sample are shown under column 2 of Table I. Another sample contained 0.1 percent of a mixture of primary amines containing a tertiary carbon atom in an alkyl group containing between 18 and 24 carbon atoms. This mixture of amines had an average molecular weight of 269, a specific gravity of .8526, a neutralization equivalent of 349 and a flash point of 265 F. (Primene JM-T manufactured by Rohm & Haas Company). The results obtained with the test sample containing this stabilizer are shown in column 3 of Table l. T o the fourth sample was added 0.1 percent of a mixture of amines having 12 to 15 carbon atoms and containing tertiary dodecyl to tertiary pentadecyl amine (Pri mene 8lT manufactured by Rohm and Haas Company). The molecular weight of this mixture of amines was 227, the specific gravity .835, the neutralization equivalent 208 and the flash point 210 F. The results obtained with this stabilizer are shown in column 4 of Table I.

Table I is a comparison between the branched chain amines representing our invention and the most active of other color stabilizing amines which we have tested. The relative activity of various amines was evaluated in a series of tests the same as those described above except 2. A color stabilized bright stock containing between that an oven temperature of 230 F. was used. The approximately .01 and 0.1 percent by weight of an amine data on these tests are given in Tables II and III. having the formula:

Table II CH3 011:! CH:

5 R-C Ha-C-CliIg-CCHz-(JNH1 1 2 3 CH3 CH3 CH3 wherein R is a member of the rou consistin of: H' 5??:?: ftf semi -i Inspection: r CH3 CH3 CH3 CH3 (EH3 1; ii and a Ha CH: CH: CH; 1 Extrapolated, 3. A color stabilized bright stock containing between Table III 150 MC Bright Stock S-P l0 Pour Aminoethyl ethauolamine Normal alkyl group Ora-is amine" Methylbenzylmonoethanolamine Cyclohexylamine Dibutylethanolamine Dicyclohexylamine Di-N-butylamine Inspection:

Color, ASIM Union Stability TestWith Copper Strip, 230 F., Color, AS'IM Union After 96 Hr 8.0

1 Extrapolated (actual color of 8.0 after 72 hours at 210 F.). 1 Extrapolated.

The normal alkyl group C1648 amine shown in Table II was identical to the amine tested in column 2 of Table I. The normal alkyl group C amine mentioned in Table V II was a mixture of amines constituting 90 percent normal octyl, 7 percent normal decyl and 3 percent normal hexyl primary amine. It was a commercial mixture (Armeen 8 manufactured by Armour and Company) having a mean molecular weight of 129 and an approximate melting point of 8.6 F. The normal alkyl group C1648 amine in Table III was a commercial mixture (Armeen 16 manufactured by Armour and Company) containing 90 percent normal hexadecyl amine, 6 percent normal octadecyl amine and 4 percent normal octadecenyl amine. It had a mean molecular weight of 244 and an approximate melting point of100 F.

The foregoing data establish that the samples containing the stabilizer of the type described herein had substantially higher stabilizing power than primary unbranched aliphatic amines. The above data also establish that primary unbranched amines are superior to the other types of amines. 1

What we claim is: 1. A color stabilized bright stock containing between approximately .01 and 0.1 percent by weight of an amine having the formula R-NH in which R is a tertiary alkyl 7 group containing 12 to 24 carbon atoms'which is attached to the amino group by the tertiary carbon atom.

approximately .01 and 0.1 percent by weight of a mixture of amines having the formula RNH in which R is a tertiary alkyl'group containing 12 to 15 carbon atoms hav- 7 specific gravity of about .85, a neutralization equivalent 7 of about 349 and a flash point of about 269 F., said tertiary alkyl group being attached to the amino group by the tertiary carbon atom.

References Cited in the file of this patent OTHER REFERENCES fTertiary-Alkyl Primary Amines; Rohm and Haas, Phila., Pa.; Sept. 1954, page 3. 

1. A COLOR STABILIZED BRIGHT STOCK CONTAINING BETWEEN APPROXIMATELY .01 AND 0.1 PERCENT BY WEIGHT OF AN AMINE HAVING THE FORMULA R-NH2 IN WHICH R IS A TERTIARY ALKYL GROUP CONTAINING 12 TO 24 CARBON ATOMS WHICH IS ATTACHED TO THE AMINO GROUP BY THE TERITARY CARBON ATOM. 